Dispersions or suspensions of solid phases in liquid phases were previously made on a batch basis, except for relatively dilute dispersions or suspensions. The solid phase was added gradually to a batch of the liquid phase in a mixer having an impeller turning at a high rpm to produce high fluid shear. As more of the solid phase was added, the viscosity of the batch increased so that further addition of the solid phase had to be reduced to a slow rate to prevent overloading the impeller.